No, the RRPproxy will forbid the AddContact during the AddDomain process.

[RESPONSE] code = ...

description = Could not create registryContact...

How can I generate an email verification request without registering a domain?

This can be useful either if you want to have a verified contact prior to a domain registration to avoid the domain suspension after 15 days, if, for any reason, the link was not clicked or if you want to update a gTLD with a new contact and not risk the domain suspension due to the aforementioned reason.